OM-2228 / Operation and Maintenance Manual
120CU20 / Series 500120 / 400 Hz. Generator Set
October 15, 2013
Chapter 2-4
Page 15
Trouble, Symptom, Condition.
Probable Cause.
Test, Check, and/or Remedy.
Load Contactor Operating Circuit (Continued).
2.
Load contactor closes when
output push-button switch is
held in CLOSED position.
Opens immediately when
switch is released.
a.
The plug interlock EF circuit on
CTL board could be defective
Place EF Bypass switch in the ON
position. If load contactor remains
closed, proceed to step
b.
b.
28.5 VDC is not reaching the
plug interlock EF circuit from
aircraft for following reasons:
Proceed as follows to find the
cause of this malfunction.
c.
Generator-to-aircraft cable
connector defective or not
plugged into aircraft receptacle
connector
Inspect cable connector plug
thoroughly for damaged E and F
terminals. Be sure plug is fully
mated with aircraft receptacle
connector and making good
contact.
d.
Aircraft rejecting power
Check aircraft on-board electrical
equipment and controls.
e.
Defective contacts in N.O.
auxiliary push-button switch
mounted on right side of
contactor
Connect a jumper lead between
terminals of N.O. auxiliary switch.
If load contactor will now remain
closed, replace N.O. auxiliary
switch or complete load contactor.
3.
Load contactor opens during
power delivery. No fault
indicated.
a.
A fault has developed in load
contactor holding circuit.
If load contactor cannot be closed
by operation of output push-button
switch, check circuit in accordance
with instructions in Trouble,
Symptom, Condition 1. If the load
contactor can be closed, but
opens as soon as power accepted
switch is released, check for
trouble under Trouble 2, above.
b.
Cable accidentally
disconnected from aircraft.
Reconnect cable.
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